Abstract

This study describes the feeding ecology of white croaker (Micropogonias furnieri) and rough scad (Trachurus lathami) larvae in the Río de la Plata Estuary (RPE) during a breeding season. The working hypotheses were that the coexistence of the species under study is favored by spatial segregation and divergence in mouth gape size, which mirrors their diet composition and trophic niche breadth (TNBs), based on prey size. Micropogonias furnieri was more abundant at the innermost stations, while T. lathami was most abundant at outermost stations of the estuary. However, their abundances were uncorrelated to environmental salinity and temperature. Micropogonias furnieri and T. lathami larvae showed differences in their gape growth patterns and in the type of preys ingested, which resulted in low dietary overlap. This did lead to differences in the TNBS and supported the prediction of the trophic differentiation hypothesis and could be interpreted as a mechanism to minimize food competition in the RPE ecosystem.

Notes

Acknowledgments

Thanks to the working team at Dirección Nacional de Recursos Acuáticos (DINARA) G. Mantero, C. Mesones, A. Martínez, and L. Ortega for their help with identification of fish larvae and for providing environmental data and access to plankton samples. Special thanks to I. Machado, D. Cambón, and R. Castiglioni (Facultad de Ciencias, Universidad de la República) for their collaboration during field work. This study was supported by contract PDT S/C/OP/36/10 (DINACYT, Uruguay). M Vera was partially funded by Programa para el Desarrollo de las Ciencias Básicas (PEDECIBA) and by Marie Curie Grant (EU- IIF – FP 6, MIF1-CT-2006-021529).